fileutils: add readDirectory

Create an abstraction layer to access directory content

Change-Id: I551475db784c0348f19cfe1d674131382c68a90c

daemon/src/dht/dhtaccount.cpp

@@ -65,7 +65,6 @@
 
 #include <unistd.h>
 #include <pwd.h>
-#include <dirent.h>
 
 #include <algorithm>
 #include <array>
@@ -614,19 +613,10 @@ DHTAccount::loadNodes() const
 std::vector<dht::Dht::ValuesExport>
 DHTAccount::loadValues() const
 {
-    struct dirent *entry;
-    DIR *dp = opendir(dataPath_.c_str());
-    if (!dp) {
-        SFL_ERR("Could not load values from %s", dataPath_.c_str());
-        return {};
-    }
-
     std::vector<dht::Dht::ValuesExport> values;
-    while ((entry = readdir(dp))) {
+    const auto dircontent(fileutils::readDirectory(dataPath_));
+    for (const auto& fname : dircontent) {
         try {
-            const std::string fname {entry->d_name};
-            if (fname == "." || fname == "..")
-                continue;
             std::ifstream ifs(dataPath_+DIR_SEPARATOR_STR+fname, std::ifstream::in | std::ifstream::binary);
             std::istreambuf_iterator<char> begin(ifs), end;
             values.push_back({{fname}, std::vector<uint8_t>{begin, end}});
@@ -635,8 +625,6 @@ DHTAccount::loadValues() const
             continue;
         }
     }
-    closedir(dp);
-
     return values;
 }
 

daemon/src/fileutils.cpp

@@ -58,6 +58,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <cerrno>
+#include <cstddef>
 
 namespace fileutils {
 // returns true if directory exists
@@ -210,6 +211,55 @@ bool isDirectoryWritable(const std::string &directory)
     return access(directory.c_str(), W_OK) == 0;
 }
 
+static size_t
+dirent_buf_size(DIR * dirp)
+{
+    long name_max;
+#if defined(HAVE_FPATHCONF) && defined(HAVE_DIRFD) && defined(_PC_NAME_MAX)
+    name_max = fpathconf(dirfd(dirp), _PC_NAME_MAX);
+    if (name_max == -1)
+#if defined(NAME_MAX)
+        name_max = (NAME_MAX > 255) ? NAME_MAX : 255;
+#else
+        return (size_t)(-1);
+#endif
+#else
+#if defined(NAME_MAX)
+    name_max = (NAME_MAX > 255) ? NAME_MAX : 255;
+#else
+#error "buffer size for readdir_r cannot be determined"
+#endif
+#endif
+    size_t name_end = (size_t) offsetof(struct dirent, d_name) + name_max + 1;
+    return name_end > sizeof(struct dirent) ? name_end : sizeof(struct dirent);
+}
+
+std::vector<std::string>
+readDirectory(const std::string& dir)
+{
+    DIR *dp = opendir(dir.c_str());
+    if (!dp) {
+        SFL_ERR("Could not open %s", dir.c_str());
+        return {};
+    }
+
+    size_t size = dirent_buf_size(dp);
+    if (size == -1)
+        return {};
+    std::vector<uint8_t> buf(size);
+    dirent* entry;
+
+    std::vector<std::string> files;
+    while (!readdir_r(dp, reinterpret_cast<dirent*>(buf.data()), &entry) && entry) {
+        const std::string fname {entry->d_name};
+        if (fname == "." || fname == "..")
+            continue;
+        files.push_back(std::move(fname));
+    }
+    closedir(dp);
+    return files;
+}
+
 FileHandle::FileHandle(const std::string &n) : fd(-1), name(n)
 {}
 

daemon/src/fileutils.h

@@ -32,6 +32,7 @@
 #define FILEUTILS_H_
 
 #include <string>
+#include <vector>
 
 #define PROTECTED_GETENV(str) ({char *envvar_ = getenv((str)); \
                                                    envvar_ ? envvar_ : "";})
@@ -56,6 +57,14 @@ namespace fileutils {
     std::string get_ringtone_dir();
     std::string expand_path(const std::string &path);
     bool isDirectoryWritable(const std::string &directory);
+
+    /**
+     * Read content of the directory.
+     * The result is a list of full paths of files in the directory,
+     * without "." and "..".
+     */
+    std::vector<std::string> readDirectory(const std::string &dir);
+
     struct FileHandle {
         int fd;
         const std::string name;